John

14 minutes ago, Deadlake said:

How long does a 10" reflector take to cool down?

I was thinking along the lines of a C9.25 or a GS0 10 F12 Cassegrain which I can put on a goto mount.

Ps: For deep sky aperture is indeed the limiting factor, for anything planets and doubles use a refractor.

My solid tube 12 inch dob cools quite quickly. It can be used to observe at lowish powers on DSO's practically straight out of the house. After around 30 minutes high power views are really pretty stable and by 40 minutes I can really push the magnification to look for that fine lunar / planetary detail.

My 130mm triplet refractor seems to have a similar cooling time. The smaller aperture refractors are somewhat quicker as you would expect. The Tak 100 seems to need very little cooling - I've split quite tight double stars with that scope straight out of the house.

I keep all my scopes in the house.

Nice report Rob

Zeta Herc can be a really tricky blighter to split. The secondary star can look like a "bump" in the diffraction ring rather than a definite star. Like a thin snake which has swallowed an orange

45 minutes ago, Stardaze said:

There doesn't appear to be a break in this heavy cloud at the moment, again this week. Really want to see the difference. 🙁

I had a couple of clear hours late last night, which was a nice surprise, but otherwise it's not been great

21 minutes ago, RobertI said:

Very interesting! Looks like the small aperture has resulted in the diffraction ring just moving past the secondary rather than being on it? Interesting about the colours too. 

It would be interesting to rig up some sort of variable aperture stop (like a camera lens has) and then play with the effects on resolution / airy disk / diffraction rings of various apertures on the fly.

Also, this website gives you information for a location you specify:

https://theskylive.com/sky/constellations/corona_borealis-constellation

6 minutes ago, IntelligentSleep7 said:

 

 

Ok Dave61 and Astro Noodles

 

what I want to find out is about the constellation Corona(e) Borealis

I want to know its behaviour, that is, what is the highest point of this constellation (its zenith(?)) and its lowest (?) point.

I want to know this very practical information. Practical in the sense that is a straightfoward information.

If you can direct me to that information, I would be very happy.

 

Northern hemisphere-wise, I have to say.

 

AS far as I can tell, this constellation never reaches the zenith of the sky, ie. the point directly above us. 

What is the behaviour of this constelation, and what does this question entail?

If the latitude and longitude has to be said for this information, it is the latitude and longitude of Lisbon, Portugal:

Latitude: 38° 43' 0.01" N
Longitude: -9° 07' 59.99" W

This knowledge I want to know, I am willing to learn about other constellations as well. But i'm addressing directly said constellation.

what do I need to know/read to learn this information? these informations.

Thank you  

 

PS: I'm just a person with things that wants to find out.

 

If you use the Stellarium planetarium software (which is free) you can enter your location then play around with dates / times to see how the position of constellations and other objects varies. You can download this software here:

http://stellarium.org/

Welcome to the forum

1 hour ago, Pixies said:

@John Do you find that colours are more obvious with smaller aperture? I see colours more clearly in the ST80 compared to the dob - but that might be magnification rather then aperture, though?

I've not compared the views directly between my 12 inch dob and a refractor on Izar for some time but you could be right. Another experiment to try

Oddly enough, the image reminded me of this from the opening sequence of one of my favourite TV programmes:

This happened a few days ago on Mars. The little drone / helecopter Ingenuity made it's 5th flight and the first where it flew to a new landing site some 129 metres from the Perserverance rover. Quite a remarkable image IMHO:

Really quite close to naked eye visibility for this nova here tonight.

I can see a pair of mag 4.85 stars just below the position of the nova and possibly the odd glimmer of 4 Cassiopeia but I can't claim the nova.

If it brightened by half a magnitude that would do nicely  

On 08/05/2021 at 13:12, RobertI said:

Yes please do John, I'd love to know.

Well I've had a go at Izar tonight with my ED120 refractor at full aperture (no problem at all at 125x) and more interestingly with the aperture stopped down to 52mm using the central aperture of the objective dust cap.

Izar was split !. The airy disks were larger and the secondary star very close to touching the primary's airy disk but there was a definite gap between the disks. The secondary star was on the inside edge of a very fine single diffraction ring created by the brighter star. The magnification used was 225x - 300x which would be a bit silly for a 52mm aperture scope but seemed to work for this target.

I was also slightly surprised to see the clear colour difference between the stars despite the small aperture.

I found this image online which nicely captures what I'm seeing although my view also includes that fine diffraction ring as well:

I was pleased as well as a little surprised by this result. I suspect that it confirms that my ED120 has a good quality objective but also that splitting Izar can be achieved with very small apertures.

While the scope was stopped down I had a go at some other doubles:

Gamma Virginis: Split

Epsilon Lyrae: One pair just about split, the closer pair touching.

Delta Cygni: Dimmer secondary star not clearly seen. Maybe just a vague hint of it ?

Iota Cassiopeia: B and C stars very dimly visible. All 3 components seemed to be split though.

Interesting experiment !

6 minutes ago, Captain Magenta said:

After being shamed by @PeterW for not bothering to venture beyond my garden (living room actually) to skirt obstructions, I went out to a local alley with a view N and with @Stu’s help found it fairly quickly. Pretty pleased, and maybe a faint hint of M52 in averted knowing exactly where it was but not sure.

M

Was this naked eye Magnus ?

On 09/05/2021 at 12:49, JeremyS said:

Has anyone spotted the current nova with NE?

A few obs in the last few hours have it at 5.3 to 5.4

Tonight I reckon the nova is very nearly as bright as 4 Cassiopeia so it must be getting close to magnitude 5.0 I would think.

I can't quite see it with the naked eye - if it were higher though, I think I could. Atmospheric extinction is probably just scrubbing enough brightness off to keep it requiring an optical aid at present.

The nova is easily visible with my smallest binoculars which are 8x25's.

Judging by this thread, you could do a lot worse than investing in some of the Baader Morpheus eyepieces:

10 minutes ago, Soligor Rob said:

So if it was between the 14mm or 12.5mm which should I buy? bearing in mind I intend to purchase the 17.5mm & 9mm when they become available.

If it was me, I would go for the 12.5mm. I think you may well find that the 14mm is a bit too close to the 17.5mm to get a lot of use. As eyepiece focal lengths get shorter, the mm increments can get smaller as well while still being useful so 12.5mm - 9mm will make sense.

1 minute ago, Littleguy80 said:

.... That only changed when I got the chance to get the Noblex....

 

I'm the same - a number of my best laid plans have changed because something interesting "came up"

The Noblex was worth changing things around for though, I'm sure. Out of production now as well.

38 minutes ago, Stardaze said:

Just reading through again and assuming your 12” is 1600mm, the comparable to your 21/13/8 core is 17/10/7 for me John. 

Yes - it's F/5.3.

I do often find shorter focal length eyepieces useful with the scope as well. Down to 4mm. Rarely anything shorter although I do have options down to 2mm if I want to be really silly

9 minutes ago, F15Rules said:

I should think that "tube security" on the mount is probably the single most important thing on most of our minds when setting up/taking down our kit?

 

Indeed Dave.

A while back I ordered one of the nice looking William Optics dovetail bars from FLO:

https://www.firstlightoptics.com/dovetails-saddles-clamps/william-optics-vixen-style-dovetail-plate.html

I was a little surprised when I found that it was just a bit narrower and my APM clamps would not clamp it securely. Luckily this was obvious before I tried using it with a scope. FLO of course took it back and gave me a full refund and also added the note to the product listing.

You do wonder though why the designer of these bars decided that a little narrower was a good idea when you consider what they are used for

I use an Altair DT bar now with the Tak and that's fine and a secure fit.

I'm also quite content with the Tak tube clamp design.

7 minutes ago, Stu said:

I have nearly done that on a few occasions, intending to loosen the clutch knob or top knob on an Ercole or giro mount, and instead starting to loosen the clamp. A timely reminder for us all to be sure which knob is being loosened!

I like the twin knobs on the ADM clamps for that reason. If you accidentally loosen one, the other still grips at least some of the dovetail bar.

14 minutes ago, Commanderfish said:

Dovetail slipped from the clamp....

 

I had that happen with my Vixen 102 ED a few years ago. I was very lucky with that because the fall was onto a stone patio but somehow the damage was restricted to the end of the dew shield and the focuser. I was able to patch it up reasonably easily.

Horrible noise though, a scope hitting the floor

Really sorry to hear that this has happened 

I can barely bring myself to look at your photo of the smashed Tak objective

At least the insurance is going to come through for you (minus excess).

Did the scope fall out of the tube clamp or was it the dovetail bar falling out of the mount clamp that caused the fall ?

6 hours ago, Sunshine said:

Just took a look at Izar, I expected a challenge but it was smack in my face obvious at about 120x or so, I guess it is due to the fact that I'm using a 102.  Would it be that much more difficult in lets say a 70mm? separation

is such that there is an unmistakable gap between these two.

 

I find it easy with 100mm / 102mm. I did it with a cheap 90mm F/11.1 achromat last week.

As the aperture shrinks the airy disks get larger and the resolving limit reduces. The uneven brightness adds quite a degree of further difficulty as well. I think I could split Izar with my old Tele Vue 70mm Ranger a couple of years ago but I can't recall definitely.

I'll try the stopped down ED120 next clear night at 52mm and see if that does it, or gets anywhere near.

Nice piece on resolution here with a lovely Damian Peach image of Izar as part of the story:

http://www.rocketmime.com/astronomy/Telescope/ResolvingPower.html

1 hour ago, teoria_del_big_bang said:

I did once manage to coincide the families holiday in Florida with a shuttle launch and saw that and yes the nosise is the thing that sticks in my mind 🙂 

Steve

I saw a Falcon 9 launch in 2017 from KSC. It was great to see something actually go up into space but it was quite a calm affair we thought. Not as dramatic as a shuttle launch I would think. I'd like to see one of the heavy lifters go up though 

6 hours ago, tony4563 said:

I have too many scopes. I don’t care...My wife thinks I’m mad but I love every one of them.

Over the years I have purchased and kept scopes of many types, but only at the maximum aperture I can comfortably handle on my own.

Weather for next few days is expected to be poor so I thought I’d take advantage of the clear Bortle 4 night  skies that had appeared last night

I tested every scope just on 2 subjects. The Hercules cluster and The Ring Nebula just to see how they fared for brightness, contrast and detail at the same magnification that looked the best to me through the eyepiece.

For me, the 120ED most disappointed on the night. Pretty obvious and expected really, as although there is no central obstruction , the 4.7" aperture just didn’t have enough light grasp compared to the rest to show the amount of stars resolved in M13’s core. The others just looked more pleasing and gave me more of a ‘’wow!’’ at the same magnification

M57 was seen but the most pleasing views were seen with averted vision. The other scopes could see the nebula directly without. Again, just more pleasing.

The 120ED is a lovely scope but I’m beginning to wonder why I still have one now. Refractors are known for their contrast but the other scopes were also too close for an argument for me.

For me, the perfect all round scope for portability, detail and brightness would be an 8" SCT or a 10" Dob.

Please take my views as only my own personal opinion from my own personal experience. Many people love the ED120. I did very much until I purchased bigger aperture scopes which then began to show its limitations, even with its unobstructed light path and great ED glass

 

 

Aperture delivers the goods on globular clusters more than on any other target IMHO. Were you expecting 120mm to beat your larger aperture scopes ?

That's not going to happen, on globular clusters at least and probably not on other DSO's. Maybe a little closer on planetary viewing but under good seeing the aperture will win there as well.

5 hours ago, Space Hopper said:

I know they did a FLT123mm version for a while that used a fast F6 LZOS optic that was a great imaging scope.

But i don't recall a 110 LZOS, only the TEC version.

On 2nd thoughts I was thinking of a WO 105mm triplet that had an LZOS objective.

Thanks for the clarification